Brake-shoe key



Sept. 10, 1935. w w CLOUSER 2,013,982

BRAKE SHOE KEY Filed May 18, 1932 2 Sheets-Sheet l INVENTOR Spt. 10, 1935. w. w. cLousER 1 BRAKE SHOE KEY Filed May 18, 1932 2 Sheets-Sheet 2 ATTORN EY Patented Sept. 10, 1935 UNITED STATES PATENT OFFICE BRAKE- SHOE KEY Application May 18, 1932, Serial No. 612,058

Claims. (01. 188-243) The present invention relates to that type of brake-shoe keys wherein a single length of spring steel is used.

An object of the present invention, having in mind the deficiencies of brake-shoe keys of such simple type, is to use for the key preferably a suitable length of leaf-spring steel or other suitable metal so constructed and formed as to enable a maximum amount of effective spring tension to be obtained when the key is inserted. in place between a brake-head and the brake-shoe, without impairing the strength and durability of the key. In order to obtain the maximum efliciency of such simple type of key, the same when inserted in position is under a maximum amount of pressure, obtained by suitably forming the bearing portions of the key with reference to the key as a whole and by preferably bowing the length of spring metal of which the key is composed outwardly and oppositely to the direction in which the driving lug of the key extends, although in some cases this arrangement may be departed from providing the spring key has certain of the desirable features of the present invention.

Still another object of the invention is to provide a key which is composed of .a minimum amount of spring steel with a maximum degree of efliciency, and which for these and other reasons is economical in use.

These being among the objects of the present invention, the same consists of certain features of construction and combinations of parts to be hereinafter described and then claimed with reference to several embodiments of the invention which are shown in the accompanying drawings and wherein Fig. 1 is a sectional elevation of a brake-head and its shoe, showing in using position a key according to the present invention;

Fig. 2 shows in full lines the key of Fig. 1 when out of use, that is when entirely free, and showing in contrast therewith a brake-shoe head in broken lines, so that the normal set of the free key with reference to the key-way of the head may be readily appreciated;

Fig. 3 is a rear elevation of the key shown in Fig. 2;

Fig. 4 is a sectional elevation of a brake-head and its shoe, showing in place a modified construction of key, and

Fig. 5 is a similar view illustrating a slight modification of the key as shown in Fig. 4. g

In so far as the brake-heads and shoes illustrated in each of Figs. 1, 4 and 5 are concerned, they are of the usual conventional construction and the same reference numerals will be used for corresponding parts. The brake-head H] has an upper end portion H and a lower end portion 52 from which there are forwardly projecting toes l3, M. It will be understood that there are two 5 toes I 3 and two toes I with a space between them, although only one of each of the pair of toes is shown. Intermediately of the length of the head It! there are two forwardly extending lugs I5, I6 provided with apertures I! which apertures constil0 tute portions of the key-way which extends along the face of the brake-head.

The brake-shoe I8 is provided at about its midlength with a rearwardly extending pair of lugs l9 (only one of which is seen), these usually being connected by a strong bridge-member usually formed of rolled steel, the construction being such that an aperture 2| is provided. When the shoe is assembled with its head by inserting the lug l 9 between the lugs I5, IS, the space allowed between 20 the planes of the oppositely facing bearing surfaces of the lugs and which are formed by the apertures through them, is comparatively small in the usual practice. Such permitted space may in practice have a transverse measurement or 5 depth of but three-eighths of an inch when the parts are new. To make use of a spring key to connect the head and shoe therefore requires that the metal of the key be of less dimension than, say, three-eighths of an inch, and that provision be made for causing the compression of the specially formed parts of the key so that the key may work properly. The upper and lower ends of the key-way of the head, or abutment surfaces, are on a line slightly in advance of the abutment surface of the shoe lug 2!, so that when a spring metal key consisting of a single length of leaf spring metal is used, such key being relatively thin as compared with three-eighths of an inch, must, in order to function properly and remain reliable, be specially formed with reference to the contracted space which it is fitted into.

One desirable form of key according to the present invention is illustrated in Figs. 2 and 3, the same consisting of a single length of leafspring steel having at its upper end a rearwardly bent driving lug 22 and the key being bowed forwardly in opposite direction to the direction in which the lug 22 extends. While the bowing may in some cases be along the line of a simple curve, the preferred key is provided with special features as contrasted with a bowing along a line of such a simple curve. The width is a little less than that of the key-way.

In Fig. 2 a free or unrestrained spring metal key is illustrated in contrast with the brake-shoe head shown in broken lines as a background, so that this figure may be compared with Fig. 1 in order to be able to note the different aspect which the key presents when in use, as in Fig. 1. At about the middle of the key, the spring metal is bent so as to form, as shown in Figs. 2 and 3, a rearwardly deflected portion 23 which extends from edge to edge thereof or breadthwise of it, the length thereof relatively to the length of the key being quite short and the same presenting a rearward substantially fiat surface of more or less area. It will be noticed that the bearing portion 23 is deflected in an opposite direction to that at which the bow of the key faces. This rearwardly deflected bearing portion 23 may be termed the major bearing portion and a rearwardly deflected bearing portion 24 adjoining it may be termed a minor bearing portion, inasmuch as it is projected rearwardly to less extent than the major bearing portion 23. The minor bearing portion 24 is much shorter in length than the major bearing portion 23, and hence is of less area.

At the front surface of the key there is located a transverse shoulder 25 which is formed by appropriately bending the strip of metal into the desired shape. The uppermost limit of the deflected major bearing portion 23 is defined by a sloping border 26 and the lowermost limit by a sloping border 2'1, the borders 26, 21 sloping in opposite direction. By reason of the forward or outward bowing of the key, there are provided rather long end portions 28 and 29 which are inclined rearwardly to the plane or highest point of the rear surface of the major bearing portion 23. At the lower end of the key there is the terminal 30 and at its upper end just below the bend caused by forming the lug 22, there is located a bearing portion 3| which extends in a plane more or less approximating that of the plane of the rear surface of the major bearing portion 23.

It will be observed that at points above and below where the lug 2| is to bear, or where the enumerated special features are developed or merged one into the other, the key is formed on gentle curves so as to avoid breaking points or lines of fracture which might otherwise occur when the key is in use.

Referring to Fig. 1, the functioning of the key in use will be described. When the shoe has been properly positioned upon the brake-head, the

- terminal of the key is inserted into the key-way of the head at a point between the usual toes l3, only one of which is shown, but before insertion the key is moved so as to direct the lug 22 rearwardly of the head, and this means that the bow of the key is directed forwardly towards the shoe. The key is then pressed down until the terminal 38 hits the forwardly presented surface of the bridge-member 20 of the lugs 2| and, to force the key further in, slight hammer blows are then given on lug 22 until the key is in the position shown in Fig. 1. The forcing of the resilient key into using position will cause the terminal 30 to pass by the rearwardly presented surface of lug I6 until the shoulder 25 snaps into engagement with the under edge of lug I6, but due to the force necessary to insert the key in the position shown, the portions of the key between the bridge-member 20 and certain portions of the lugs I5, IE will be in a state of compression, thereby tending to hold the key in place. This state of compression means that a part of the key between the border 26 and the inclining end portion 28 will be forcibly brought to bear upon the lug l and that the minor bearing portion 24 will be forcibly and squarely seated against the lug i6. Furthermore, the end bearing portion 3! just under the lug 22 will be forcibly seated against the upper end of the head H3, at a point between the two usual toes l3, while the lower terminal 30 will be forcibly pressed against the lower end l2 of the head. In other words, the inclined portions 28, 29 of the key will also be in a state of compression, the shoulder 25 preventing the key from working upwardly,

It will therefore be seen that the maximum bowing of the key when free, as in Fig. 2, is reduced to a minimum when the key is in use, due to the compressed condition of the key caused by forcing'the same into place. Expressed in different terms, it will be seen that on account of the maximum bowing of the specially formed resilient key towards the front, the normal set of the key is such as would position the rearwardly deflected bearing portions 23, 24 of the key on about, or a little in front of, a line connecting the terminals of the key if the same could be inserted without force and without causing compression, but when the key is compressed into the restricted space as it must be, the rearwardly deflected bearing portion is in a position 30 well to the rear of the position which it takes if the key is free and unrestricted. The key therefore exerts a maximum of spring pressure and is not likely to work up out of place.

In Fig. 4 a modified construction of the key is shown in using position, the same having a driving lug 32. When such key is free, it is bowed forward similarly to the key shown in Figs. 2 and 3. The rearwardly deflected bearing portion 33 is formed with rearward corrugations 34, 35 joined with the inclined end portions 36, 31. The rearwardly deflected portion 33 extends breadthwise of the key, the same as in Figs. 2 and 3, but is of different shape to the corresponding feature there shown. The corrugations 34, 35 increase the height relatively to the length of the key and serve to form between them a depressed bearing part 38 to receive the bridge-member of the shoe lugs 2|. Here the rearwardly deflected portion 33 is also in a state of compression between the lugs of the shoe and the lugs of the head, and the corrugations 34, 35 define the position of the key and are intended to prevent the key from moving downwardly or upwardly with respect to the position shown. Here also the inclined end portions 36, 3'! will also be in a state of compression, the lower end of the key having a bearing portion 39 forced against the lower end of the head. The terminal 40 of the key is bent or deflected rearwardly so as to provide a snap fastening tending to prevent the key from shifting upwardly, thereby supplementing the action of the transverse corrugation or shoulder 35.

Referring to Fig. 5 there is shown a slightly modified form of the construction shown in Fig. 4. In Fig. 5 the key is also shown in using position and under compression similarly to the other forms. It is provided with a rearwardly extending driving lug 4| and with a rearwardly deflected bearing portion 42 formed with a rearward corrugation 43 which acts similarly to the corrugation 35 of Fig. 4. The corrugation 35 of Fig. 4 and corrugation 43 of Fig. 5, each act as a stop shoulder similarly to the shoulder 25 in Fig. l to restrain any tendency of the spring key to work upwardly out of the key-way. There is no corrugation in Fig. corresponding to the corrugation 34 of Fig. 4, and otherwise the construction and form of the key is substantially the same as the key shown in Fig. 4.

Obviously the invention shown and described is susceptible to more or less modification without departing from the scope of the appended claims.

What I claim is:

1. A brake-shoe key, including a single length of leaf-spring metal, having a rearwardly deflected portion which extends transversely along the breadth of the key, is very short relatively to the length of the key and is located at the middle portion of the key, for engaging a part of a shoe, the key having a driving lug at one end, extending outwardly from the breadth of the key, and the key being bowed towards its shoe receiving face, and having a pronounced shoulder extending across the breadth of the front of the key in a position for engagement under a member between the ends of the brake-shoe head.

2. A brake-shoe key, including a single length of leaf-spring metal having a rearwardly deflected portion extending along its breadth, and substantially parallel, rearward, corrugations forming stop shoulders extending across the deflected portion and defining the extreme depth of such deflected portion and also the rear vertical width of such deflected portion.

3. A brake-shoe key, including a single length of leaf-spring metal having a rearwardly deflected portion extending along its breadth, and a rearward corrugation forming a stop shoulder extending across the deflected portion and defining the lower end of such deflected portion and the 5 extreme depth thereof.

4. A brake-shoe key formed from a single length of bowed leaf-spring metal having in its middle portion an integral, pronounced upwardly presented stop shoulder extending across the breadth thereof, and located in a position for engaging the under side of a member positioned between the ends of the key-way of the brake-shoe head.

5. Abrake-shoe and its head provided with a key-way and abutment means between the head and shoe, in combination with a key consisting of a single length of leaf-spring metal extending through the key-way and bearing upon inner surfaces of the shoe and head in opposite directions, the key when free from pressure having a maximum bowed out shape, the key when positioned being in a state of compression and the degree of its maximum bowing being thereby decreased, and the key having an integral pronounced, upwardly presented, stop shoulder extending across the breadth thereof, and located near the mid-length of the key in a position to snap under a portion of the head which intercepts the length. of the key-way.

WILLIAM W. CLOUSER. 

